Modern fluxing materials and analysis of their impact on silicate structures: A review

Flux materials enhance the energy efficiency of ceramic and glass-ceramic materials production. Traditional fluxes like feldspars and alkaline carbonates often require significant quantities (over 10 wt%) in raw mixtures. In contrast, borates and fluorides offer promising alternatives with strong fluxing effect. The fluxing effect of borates is based on the influence of their oxide constituents - Na2O and B2O3. Boron oxide acts as a glass-forming agent, leading to a formation of glassy phase at lower temperatures. Sodium oxide effectively depolymerizes silicon-oxygen network and reduces its melting temperature. The fluxing effect of fluorides is described by two primary hypotheses: the Dietzel-Buerger hypothesis, suggesting fluoride-induced depolymerization of silicon-oxygen network, and the Kogarko-Krigman hypothesis, proposing fluoride association with basic cations, affecting a microheterogeneity in silicate melts. However, the precise mechanism of fluoride fluxing effect still isn't created. The analysis of flux materials allows development of energy-efficient and cost-effective processes for silicate material synthesis.